class_docstr: Object representing a set of rows by keeping a list of RowKeys and
  RowRanges that the set consists of.
code: def append(self, row_or_range):
      if isinstance(row_or_range, str):
          core_ops.bigtable_row_set_append_row(self._impl, row_or_range)
      else:
          core_ops.bigtable_row_set_append_row_range(
              self._impl, row_or_range._impl
          )
  
file_path: io/tensorflow_io/python/ops/bigtable/bigtable_row_set.py
imports: from tensorflow_io.python.ops import core_ops
  from tensorflow_io.python.ops.bigtable import bigtable_row_range
  from typing import Union
label_desc: Use image node_id 3 for calling the RowSet obj's underlying member method code with example usage: obj.append(row_or_range) without return types